Earth's slower rotation linked to warming

By Seth Borenstein INQUIRER WASHINGTON BUREAU

Posted: February 18, 2002

WASHINGTON — Feeling as if the day is dragging? Blame global warming.

Increased man-made carbon dioxide, a global-warming gas in the atmosphere, is slowing Earth's rotation, according to a study by Belgian scientists published last week in the journal Geophysical Research Letters.

It's not much of a slowdown - about 1.7 microseconds, or 1.7 millionths of one second, a year, according to coauthor Michel Crucifix, a climate researcher at Catholic University of Louvain in Belgium.

The slowdown occurs because extra carbon dioxide expands the mass of Earth's atmosphere from Earth's surface. The change slows Earth's rotation the way the spins of ice skaters slow when they extend their arms.

Crucifix's findings were based on runs of 14 computer models.

Even without global warming, Earth has been slowing, mostly because the gravitational pull of the moon has been acting as a brake.